Smartwool Men's Intraknit Thermal Merino Base Layer Crew Black White Size Small. Very Good preowned condition - small blemish on back of neck - see pictures. See photos for measurements. The most advanced performance base layer is 3D-knit to provide a tailored fit with mesh ventilation to balance warmth and breathability. This minimalist-style crew is anything but insignificant. The Men's Intraknit™ Thermal Merino Base Layer Crew is a lightweight, super-moveable top, made for all of your most extreme cold-weather activities. With Merino wool yarns and gender-specific ventilation perfectly placed to maximize thermoregulation and breathability during high-intensity activities, it helps amplify moisture management, movement, and comfort.